it has prevented me from writing too much

Donald Hall: Do you think that the optimal career for a poet would involve no work at all but writing and reading? 

T.S. Eliot: No, I think that would be... —but there again one can only talk about oneself. It is very dangerous to give an optimal career for everybody, but I feel quite sure that if I’d started by having independent means, if I hadn’t had to bother about earning a living and could have given all my time to poetry, it would have had a deadening influence on me. 

Hall: Why? 

Eliot: I think that for me it’s been very useful to exercise other activities, such as working in a bank, or publishing even. And I think also that the difficulty of not having as much time as I would like has given me a greater pressure of concentration. I mean it has prevented me from writing too much. The danger, as a rule, of having nothing else to do is that one might write too much rather than concentrating and perfecting smaller amounts. That would be my danger.

- T.S. Eliot, from his Paris Review interview. You can read the whole thing here.